ZyXEL Communications P-334WT Support Notes page 167

2. Setup ZyWALL
Similar to the settings for P-334WT, ZyWALL is configured in the same way.
1. Using a web browser, login ZyWALL by giving the LAN IP address of ZyWALL in URL field.
2. Click Advanced, and click VPN tab on the left.
3. On the SUMMARY menu, Select a policy to edit by clicking Edit.
4. On the CONFIGURE-IKE menu, check Active check box and give a name to this policy.
5. Select IPSec Keying Mode to IKE and Negotiation Mode to Main, as we configured in P-334WT.
6. Source IP Address Start and Source IP Address End are PC 2 IP in this example. (the secure host behind ZyWALL)
7. Destination IP Address Start and Destination IP Address End are PC 1 IP in this example. (the secure remote host)
Note: You may assign a range of Local/Remote IP addresses for multiple VPN sessions.
8. My IP Addr is the WAN IP of ZyWALL.
9. Secure Gateway IP Addr is the remote secure gateway IP, that is P-334WT's WAN IP in this example.
10. Select Encapsulation Mode to Tunnel.
11. Check the ESP check box. (AH can not be used in SUA/NAT case)
12. Select Encryption Algorithm to DES and Authentication Algorithm to MD5, as we configured in P-334WT.
13. Enter the key string 12345678 in the Preshared Key text box, and click Apply.
See the screen shot: